Delta, JetBlue, Frontier, Spirit, and Allegiant come to mind. None of the carriers that fly regional jets for American and United have 737s of any sort. If the PR is that bad both Alaska, American, and United are in a much better position to scrap their MAXs than Southwest.
Now if the 787 is grounded or loses ETOPS certification, that'll be a much bigger hit for the big US airlines.